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R. T. REID nJ.V L. MGDON'N'ELL. TELEPHONE SYSTEM.

Patented Feb. 1, 1898 @gi a z 2l T 2o B u... B

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ROBERT T. REID AND JAMES L. MCDONNELL, OF TAOOMA, WASHINGTON, ASSIGNORS OF ONE-HALF-TO FRANK C. ACARDIN AND JOHN T. BIBB, OF

SAME PLACE.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 598,183, dated February 1, 1898.

Application nea Mey 7, 1897. serai No. 635,528. or@ model.)

To ctZZ whom t may concern:

Be it known that we, ROBERT T. REID and JAMES L. MGDONNELL, of Tacoma, in the county of Pierce and State of Washington, have invented certain new and useful Improvements in Telephone Systems; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Our invention relates to an improvement in telephone systems, the object of the invention being to increase the efficiency of partylines on which a series of subscribers-telephone apparatus is placed by the provision of simple and efficient means whereby to render it impossible for a subscriber on such party-line to cut in his telephone while the line is being used by another subscriber, and thus prevent one subscriber from interrupting or overhearing the conversation of another subscriber.

A further object is to provide a subscriberstelephone apparatus with means whereby to denote whether or not the line is in use.

With these objects in View the invention consists in certain novel features of construction and combinations and arrangements of p In the accompanying drawings, Figure l is a diagrammatical View illustrating our invention. Fig. 2 shows, theoretically, the connections made at the central oflice between two party-lines to enable a subscriber on one of them to converse with ,a subscriber on the other. Fig. 3 is a detail view of the signaling or indicating device used in connection with a subscribers instrument for notifying the subscriber-of the condition of the line. Fig. dis a modification of the signaling device.

A B represent the main conductors of a party-line, in circuit with which at the central office a battery l, an annunciator 2, and a resistance 3 are included. Subscribers telephones and our improved lock-out devices are arranged in parallel between the main conductors. Any desired number of such sets of subscribers apparatus may be employed on each party-line. In Fig. l of the drawings four sets of subscribers apparatus are shown, and each set is a duplicate of the others. A detailed description of oneset will therefore suffice for all.

O represents the subscribers transmitter, D the hand-phone, E the switch-arm on which the hand-phone hangs, said switch-arm being connected with the line-wire A by means of a conductor d, and F represents the contactscrew with which the switch-arm engages after the han d-phone has been removed therefrom, all of these devices being arranged in series in a multiple-arc circuit between the line conductors A B.

The switch-arm E is pivotally supported at or near its center and a spring t tends to cause the hooked end thereof to approach the contact pin or screw F to close the telephone- Y circuit,said switch-arm being normally maintained removed from the contact pin or screw by means of the weight of the hand-phone. The inner end of the switch-arm is beveled,

as at 5, and terminates immediately over a beveled tooth or projection 6 at the upper end of a lever 7. The lever 7 is pivotally supported near its lower end and is maintained in its normal position with the tooth d under the end of the switch-arm by means of aspring S. Adjustable stops 9 10 are provided to limit the movements of the lever 7. An electromagnet l2 is disposed near the lever 7 and adapted to attract an yarmature ll, carried by said lever. The coil or helix of the magnet 12 is of high resistance as compared with the m ultiple-arc telephone-circuit and forms part of a normally open circuit, including the lever 7, switch-arm E, and conductor a.

From the construction and arrangement of parts above described it will be seen that when the hand-phone of one subscribers-telephone apparatus (say at subscribers station No. l) is removed the hooked end of the switch-arm Will commence to move toward the screw F; but its actual contact at this time with said screw will be prevented by engagement with the lever 7. As soon as this occurs a circuit, including the magnet 12, lines A B, battery 1, resistance 3, and annunciator 2, will be closed. The magnet 12 will now attract its armature and thus move the toothed end of lever 7 out of the path of the beveled end of switch-arm E, whereupon the latter will be permit-ted to complete its movement and making contact with the screw F close the multiple-arc circuit, which includes the subscribers telephone, and thus put the subscriber in communication with the central office, who will know from the dropping of annunciator 2 that he has called. Should now another subscriber (say at subscribers station No. 2) remove his hand-phone from the switch-arm, the latter would turn on its fulcrum and engage the cooperating lever 7 and close the circuit which includes the magnet 12 of the apparatus at subscribers station No. 2. The coil of said magnet 12 is, as above explained, of high resistancemuch higher, in fact, than the resistance of the multiple-arc telephone-circuit-and consequently when any one of the telephone-circuits is closed all the magnets 12 will in effect be shunted, so that should a subscriber at station No. 2 (or at any other station except the one at which the telephone is in use) remove his hand-phone from the switch-arm the circuit of the cooperating magnet 12 would be closed; but this circuit would not receive enough current to energize the magnet sufficient-ly to result in the withdrawal of lever 7 from the path of the switch-lever, and this result will be further insured by the use of the resistance 3. The switch-arm E at station No. 2 will thus be prevented from moving far enough to close its cooperating telephone-circuit while the telephone-circuit at station No. 1 (or at any other station) is closed.

It is desirable that some means be provided whereby a subscriber may be notiied when he desires to use the line whether or not the line is in use by another subscriber. For

- this purpose a bell 11 may be employed and adapted to be struck by a hammer 15 at the free end of a spring-arm 16, secured to the switch-arm of each subscribers-telephone apparatus. The bell will be so disposed with respect to the hammer that it will not be struck by the latter unless the switch-arm be permitted to move to the full extent of its throw and make contact with the screw F. Thus it will be seen that if the bell be sounded when a subscriber removes his hand-phone the subscriber will be notied that the line is not in use and that his call has been indicated at the central office.

It is evident that the signal for denoting the condition of the line may be arranged to be operated electrically instead of mechanically when a subscriber removes his handphone from its hook. For instance, the arrangement shown in Fig. 6 may be adopted. In. this form of the invention a magnet 17 is included in the telephone-circuit of each subscribers apparatus and adapted to actuate a bell-hammer 18, arranged to strike a bell 19.

It is apparent that with this arrangement when the hand-phone has been removed and the switch-arm E has moved far enough to close the telephone-circuit the magnet 17 will be energized and the bell sounded.

As before mentioned, it is desirable to em- -ploy a resistance, such as indicated at 3, to

assist in insuring the practical inactivity of the magnets 12 when one of the multiple-arc telephone-circuits is closed.` If desired, however, a separate resistance might be omitted by making the coil of the annunciator-magnet of high resistance.

Should two subscribers on the same partyline desire to converse, their telephones may be included in circuitwith each other by cutting out the resistance 3 at the central ofiice or by increasing the battery-power, or both, and this can be readily accomplished by means of any suitable switch.

When the subscribers telephone at station No. 1 was included in circuit wit-h the central Office, as above explained, the beveled end of the switch-arm E became disposed under the tooth or projection on the lever 7 when said switch-arm made contact with the screw F; but when the subscriber again hung his handphone on the hooked end of the switch-arm the latter was turned on its fulcrum, and the beveled end thereof engaging the beveled projection on the end of the lever 7 forced the latter back against the resistance of the spring` 8 and assumed its normal position above and out of contact with the projection 6 on lever 7.

Fig. 2 represents, theoretically, two partylines connected together at the central office, so that a subscriber on one may converse with a subscriber on the other. A B and A B represent two party-lines; 2O 21, the resistances (corresponding with the resistance 3 shown in Fig. 1) to aid the locking devices, as above explained; 22, an annunciator forindicating to the operator at the central office when the connection is no longer desired, and 23 represents the battery for operating the annunciator 22. The annunciator 22 is so constructed as to have a high self-inductive capacity to prevent its short-circuitin g the talkin g-circuit. It is obvious that if the annunciator 22 is not desired the conductors A and A and B and B' may be simply connected together without the battery 23 or the resistances 2O 21. There would thenbe no battery on either line to operate the locking-magnets, and consequently no subscribers telephone which was not already in circuit could be cut in and a conversation between two subscribers could not be interfered with or overheard by other subscribers.

It will be understood that no special switchboard arrangements are necessary for applying our improvements with the exception of placing resistances in each line to aid the hand-phonesand transmitters in shuntin g the locking-magnets at the proper time. These IOO IIO

resistances may be placed outside the switchboard, if desired.

Other slight changes might be made in the details of construction of our invention without departing from the spirit thereof or limiting its scope, and hence we do notwish to limit ourselves to the precise details herein set forth.

Our improvements are simple in construction, can be easily applied and used in connection with any desired construction of switchboard, and are effective in all respects in the performance of their functions.

Having fully described our invention, what we claim as new, and desire to secure by Letters Patent, is-

1. In a telephone system, the combination with the line, a series of telephones thereon and lock-out devices for said telephones, of a normally open circuit for each telephone, a normally open circuit for each lock-out device of higher resistance than the telephonecircuit and a switch-arm common to both of said circuits, substantially as set forth.

2. In a telephone system, the combination with two line conductors, of a series of telephone apparatus arranged between said line conductors, each apparatus comprising a telephone and a lock-out device arranged in parallel between the line conductors, the circuit of the lock-out device being of greater resistance than the telephone-circuit and a switcharm common to both circuits and constructed and arranged to maintain both of said circuits norm ally open,substantially as set forth.

3. In a telephone system, the combination with two line conductors and a source of electrical energy, of a series of telephone apparatus arranged between said line conductors,

each apparatus comprising a telephone and a lock-out device arranged in parallel between the line conductors, the circuit of the lock-out device being of higher resistance than the telephone-circuit, a switch common to both circuits and arranged to maintain both normally open and a resistance included in the line-circuit, substantially as set forth.

4. In a telephone system, the combination with two line conductors and a source of electrical energy, of a series of telephone apparatus arranged between said line conductors, each apparatus comprising a telephone and a swi tch arranged in a normally open multiplearc circuit and a lock-out device consisting of an electromagnet, a pivoted lever and said switch, said lock-out device being included in a circuit of higher resistance than the telephone-circuit and in parallel therewith, substantially as set forth.

5. In a telephone system, the combination with two line conductors and a source of electrical energy, of a series of telephone apparatus, arranged in parallel between said line conductors, each apparatus consisting of a switch-arm connected with one line conductor, a contact device to be engaged by said circuit, a battery, an annunciator and a resistance, of a series of telephone apparatus arranged between said line conductors, each apparatus comprising a switch-arm pivotally supported between its ends and electrically connected with one of the line conductors, a normally open multiple-arc telephone-circuit including a telephone and a contact-screw and a multiple-arc circuit of higher resistance than said telephone-circuit including an electromagnet and a lever normally disposed in the path of one end of the switch-arm, substantially as set forth.

7. In a telephone system, the combination with two party-lines adapted `to be connected together at the central office, each party-line comprising two line conductors, of a series of telephones arranged in parallel between the conductors of each line, lock-out devices for each telephone and included in circuits of higher resistance than the telephone-circuits, a resistance for each party-line and a ringo annunciator and a battery arranged in multiple arc with both party-lines,I substantially as set forth:

S. The combination in a telephone system, of two lin'e conductors, a series of telephone apparatus arranged between said line con-4 ductors, each apparatus comprising a telephone and a lock-out device each arranged in parallel between said line conductors, a switch-arm common to both the telephone and the lock-out circuits and devices at the central office arranged to actuate said lock-out devices to control the movements of said switch-arm, substantially as set forth.

9. In a telephone apparatus, the combination with the line, of a telephone-circuit and a lock-out circuit, a magnet in the lock-out circuit, a pivoted switch-arm common to both of said circuits, a contact-point in the path of movement of one end of said switch-arm, a pivoted arm in the path of movement of the other end of said switch-arm, said pivoted IOO IIO

arm b eing under the control of the magnet in the lock-out circuit, a bell, and devices intermediate of the switch-arm and the bell and cooperating therewith to sound the bell when the switch-arm engages the contact-point to close the telephone-circuit, substantially as set forth.

l0. In a telephone apparatus, the combination with a switch-arm pivoted between its ends, a lock-out arm in the path of movement of one end of said switelrarm, means for movspecification in the presence of two subscribing said look-out amm, a contact-point in the ing Witnesses.

line of movement of the other end of said 1 switch-arm, a bell, and a bell-hammei fixed 5 to said switch-arm and adapted to strike the L bell when said switch-arm engages said oon- Viitnesses:

tact-point, substantially as set forth. ROBERT WINGATE,

In testimony whereof We have signed this R. J. DAVIS. 

